Liquid level



June 19, 1928..

F. L. HUNT ET'AL IjIQUID LEVEL Filed 001:. 31, 1924 Patented ale 19, 13%28.

UNETED srATEs Leia-see PATENT OFFICE.

FRANKLIN L. HUNT AND KARL H. BELT, OF WASiHIINGTON, DISTRICT OF COLUMBIA.

LIQUID LEVEL.

Original application filed June 8, 1921,

This invention relates to liquid levels and more particularly to those types of bubble tubes or bubble lenses used in sextants, range finders, transits and the like, although the use of this invention is not necessarily restricted to these types of instruments.

It is the ob ect of this invention to provide means for compensating for temperature changes affecting the levelling bubble.

In instruments of precision inwhich the ordinary sealed bubble level is used, the sure of the bubble is materially affected by heat and cold and its size is sometimes so changed as to make the bubble level useless for its IEPHIPOSQ; It is to this end that we provide novel means forregulatingthe size. of the bubble for all conditions of temperature.

The invention is illustrated in the accompanying drawing as applied, by way of an example, to a sextant using a bubble lens. The particular sextant illustrated forms the subject matter of our co-pending application, Serial No. 474,582, now Patent No.

1,531,615, filed June 3, 1921, the present ap- 5 plication being a division of said co-pending application.

In the accompanying drawings r Fig. 1 is a vertical, longitudinal section through a sextant using a bubble level which embodies our invention.

Fig. 2 is a section through the bubble level and the adjusting or regulating means.

lens showing t e reference marks.

Referring more particularly to the drawings, it is seen that the frame 1 of the sextant supports an adjustable index mirror 2, a collimatin lens 3, a'bubble mirror 4 and a level bub le 5, thus'forming the optical system of the'sextant' In. case of night observations, the electric light 6 is used to illuminate the level bubble. -The constructioh of the level bubble an its adjustment is shown more clearly in Figure 2. The bubble chamber 10'is formed by two circular top and bottom lenses 11 and 13 and "an intermediate annular spacer 12, the lenses 11 and 13' being of glass or" other transparent material. On the frame 5o 1 and at one side of the bubble chamber, a

reservoir chamber 15 is formed. This chamber, 1s always 1n communicatlon with the bubble chamber 10 by means of the tubular connection or hollow screw 14. A flexible diaphragm 16, preferably of metal, is placed in the reservoir chamber 15, in a,

medial position therein and clamped between the rings 17 and 18. The outer side of the chamber 15 is closed by the cap 19. An adjusting screw 20 is threaded through cap 19 and bears against the diaphragm 16.

circles 21 etched in the glass which may be used as reference marks to accurately center the bubble and also to aid in" adjusting the size of the bubble.

The bubble chamber and reservoir are filled with a suitable fluid or liquid, allowing a small air space, however, to form the level bubble5, as shown in Figure 1. Upon initial installation, the diaphragm 16 is distorted and placed under tension by ad justing screw 20. It is apparent by such The -t0p lens 11 may be provided with concentric a construction that the amount of fluid or.

liquid in the chamber 10 may be varied so as to regulate the size of bubble 5by merely .turning the adjusting screw 20 either in or out. By such a construction. it is possible to have the bubble of a certain size, for example, the size of the inner reference mark 21, for all readings whether taken at night a or during the daytime. Fig. 3 is a lan view of the level bubble We claim- 1. An adjustable liquid level comprisin a bubble chamber, a reservoir chamber, 'sai bubble. and reservoir chambers having a communicating connection, a flexible diaphragm in said reservoir, and an adjusting screw for distorting said diaphragm.

2. In a liquid level, the combination of a bubble chamber, and te perature compensating means comprisin an auxiliary reservoir, a diaphragm in said reservoir, and

means for causing movement ofsaid diaphragm 1n both directions.

In testimony whereof we aflix our signe tures. i

FRANKLIN L. from. KARL BEIJ. V 

